Australian long-finned pilot whales (Globicephala melas) emit stereotypical, variable, biphonic, multi-component, and sequenced vocalisations, similar to those recorded in the northern hemisphere

Rachael Courts,Oliver Boisseau,K Curt Jenner,Christine Erbe,Rebecca Wellard,Micheline-N Jenner

doi:10.1038/s41598-020-74111-y

Rachael Courts, Oliver Boisseau + Show 4 more

Open Access

https://doi.org/10.1038/s41598-020-74111-y

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Journal: Scientific Reports	Publication Date: Nov 26, 2020
Citations: 10	License type: open-access

Affiliation: Curtin University, Center for Whale Research

Abstract

While in the northern hemisphere, many studies have been conducted on the vocal repertoire of long-finned pilot whales (Globicephala melas), no such study has been conducted in the southern hemisphere. Presented here, is the first study on the vocalisations of long-finned pilot whales along the southern coast of mainland Australia. Multiple measures were taken of 2028 vocalisations recorded over five years in several locations. These vocalisations included tonal sounds with and without overtones, sounds of burst-pulse character, graded sounds, biphonations, and calls of multiple components. Vocalisations were further categorised based on spectrographic features into 18 contour classes. Altogether, vocalisations ranged from approximately 200 Hz to 25 kHz in fundamental frequency and from 0.03 s to 2.07 s in duration. These measures compared well with those from northern hemisphere pilot whales. Some call types were almost identical to northern hemisphere vocalisations, even though the geographic ranges of the two populations are far apart. Other call types were unique to Australia. Striking similarities with calls of short-finned pilot whales (Globicephala macrorhynchus) and sometimes sympatric killer whales (Orcinus orca) were also found. Theories for call convergence and divergence are discussed.

Highlights

While in the northern hemisphere, many studies have been conducted on the vocal repertoire of long-finned pilot whales (Globicephala melas), no such study has been conducted in the southern hemisphere
A total of 2028 long-finned pilot whale vocalisations were recorded at sufficient quality for analysis
This article provides the first description of long-finned pilot whale vocalisations recorded off southern Australia

Summary

Introduction

While in the northern hemisphere, many studies have been conducted on the vocal repertoire of long-finned pilot whales (Globicephala melas), no such study has been conducted in the southern hemisphere. Vocalisations ranged from approximately 200 Hz to 25 kHz in fundamental frequency and from 0.03 s to 2.07 s in duration These measures compared well with those from northern hemisphere pilot whales. Odontocetes, in general, emit three types of vocalisations: whistles, burst-pulse sounds, and clicks[6]. Whistles are continuous tonal sounds, consisting of a fundamental contour with or without harmonically related overtones They are likely used to encode group or individual identity[7,8]. Some odontocete species further produce vocalisations that have aspects of both whistles and burst-pulse sounds. Multi-component vocalisations comprise two or more components in immediate succession, without any gap in time These components can be of whistle or burst-pulse type, or, are biphonations. Whistles and burst-pulse sounds differ on a species, population, and sometimes individual level. Whistles and burst-pulse sounds of the same species may further change with geographic region, habitat, and ecological factors[4,25], and in response to ambient n oise[26,27]

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